Devices have been previously developed to induce relaxation and relieve stress by providing combinations of light and sound. One such device drives optical sensors to provide light at specific brainwave frequencies while simultaneously providing musical signals, e.g., voice or instrumental music. Such systems employ a forcing function that seeks to alter a user's brainwave to a dominant predetermined frequency, usually defined in the well-known beta, alpha, theta, or delta states. Such systems attempt to modify brainwaves to induce feelings of relaxation in the user.
Another prior device modulates each sound channel of a stereophonic musical signal with a rectangular wave at the desired brainwave frequency to provide a similar effect. Using this device with the eyes closed, light signals are viewed that produce ideas of time and space as well as nonproducable or chaotic effects. Such systems produce limited lighting effects because the light they produce is driven by a constant rectangular wave.
Additionally, other previously developed relaxation devices provide light that is dependent on the amplitude of a musical signal. Again, such systems are limited in the variations of light emissions they are capable of providing. These prior devices do not provide appropriate stimulation to modify brainwaves and induce a user's sense of relaxation or provide acceptable entertainment value to the user. To the contrary, such prior devices may induce a sense of confusion in the user. Confusion that is similar to a trance but is more related to the operation of the brain cross-correlating information from both audio and visual senses. Confusion occurs when listening to music when one ear hears a musical signal at one frequency while the other ear hears a musical signal at a different frequency.